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Groups > comp.lang.c++ > #70572
| Newsgroups | comp.lang.c++ |
|---|---|
| From | Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> |
| Subject | Probably UB but I am finding it hard to give a fuck (C++ swizzle) |
| Organization | Jupiter Mining Corporation |
| Message-ID | <cYwKF.3051$vj3.487@fx10.dcg> (permalink) |
| Date | 2019-12-18 21:34 +0000 |
Hi!
The following is the base class of my vector class (the mathematical vector not the container) so I can do things like:
vec3 v1 = { 1.0, 2.0, 3.0 };
vec2 v2 = v1.xy;
double z = v1.z;
vec4 v3 = v1.xyzz;
So we have an anonymous union of an anonymous struct and some swizzles and I suspect it is full of UB but I am finding it hard to care as I cannot see any other way of doing this.
Collective thoughts/wisdom?
// swizzle_array.hpp
/*
neogfx C++ GUI Library
Copyright (c) 2019 Leigh Johnston. All Rights Reserved.
This program is free software: you can redistribute it and / or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <neogfx/neogfx.hpp>
#include <neogfx/core/swizzle.hpp>
namespace neogfx
{
namespace math
{
template <typename V, typename T, uint32_t Size>
struct swizzle_array
{
typedef T value_type;
typedef std::array<value_type, Size> array_type;
typedef V vector_type;
union
{
array_type v;
struct // todo: alignment, padding?
{
value_type x;
value_type y;
value_type z;
};
swizzle<vector_type, array_type, 2, 0, 0> xx;
swizzle<vector_type, array_type, 2, 0, 1> xy;
swizzle<vector_type, array_type, 2, 0, 2> xz;
swizzle<vector_type, array_type, 2, 1, 0> yx;
swizzle<vector_type, array_type, 2, 1, 1> yy;
swizzle<vector_type, array_type, 2, 1, 2> yz;
swizzle<vector_type, array_type, 2, 2, 0> zx;
swizzle<vector_type, array_type, 2, 2, 1> zy;
swizzle<vector_type, array_type, 2, 2, 2> zz;
swizzle<vector_type, array_type, 3, 0, 0, 0> xxx;
swizzle<vector_type, array_type, 3, 0, 0, 1> xxy;
swizzle<vector_type, array_type, 3, 0, 0, 2> xxz;
swizzle<vector_type, array_type, 3, 0, 1, 0> xyx;
swizzle<vector_type, array_type, 3, 0, 1, 1> xyy;
swizzle<vector_type, array_type, 3, 0, 1, 2> xyz;
swizzle<vector_type, array_type, 3, 1, 0, 0> yxx;
swizzle<vector_type, array_type, 3, 1, 0, 1> yxy;
swizzle<vector_type, array_type, 3, 1, 0, 2> yxz;
swizzle<vector_type, array_type, 3, 1, 1, 0> yyx;
swizzle<vector_type, array_type, 3, 1, 1, 1> yyy;
swizzle<vector_type, array_type, 3, 1, 1, 2> yyz;
swizzle<vector_type, array_type, 3, 1, 2, 0> yzx;
swizzle<vector_type, array_type, 3, 1, 2, 1> yzy;
swizzle<vector_type, array_type, 3, 1, 2, 2> yzz;
swizzle<vector_type, array_type, 3, 2, 0, 0> zxx;
swizzle<vector_type, array_type, 3, 2, 0, 1> zxy;
swizzle<vector_type, array_type, 3, 2, 0, 2> zxz;
swizzle<vector_type, array_type, 3, 2, 1, 0> zyx;
swizzle<vector_type, array_type, 3, 2, 1, 1> zyy;
swizzle<vector_type, array_type, 3, 2, 1, 2> zyz;
swizzle<vector_type, array_type, 3, 2, 2, 0> zzx;
swizzle<vector_type, array_type, 3, 2, 2, 1> zzy;
swizzle<vector_type, array_type, 3, 2, 2, 2> zzz;
};
};
template <typename V, typename T>
struct swizzle_array<V, T, 1>
{
typedef T value_type;
typedef std::array<value_type, 1> array_type;
typedef V vector_type;
union
{
array_type v;
struct // todo: alignment, padding?
{
value_type x;
};
swizzle<vector_type, array_type, 2, 0, 0> xx;
swizzle<vector_type, array_type, 3, 0, 0, 0> xxx;
};
};
template <typename V, typename T>
struct swizzle_array<V, T, 2>
{
typedef T value_type;
typedef std::array<value_type, 2> array_type;
typedef V vector_type;
union
{
array_type v;
struct // todo: alignment, padding?
{
value_type x;
value_type y;
};
swizzle<vector_type, array_type, 2, 0, 0> xx;
swizzle<vector_type, array_type, 2, 0, 1> xy;
swizzle<vector_type, array_type, 2, 1, 0> yx;
swizzle<vector_type, array_type, 2, 1, 1> yy;
swizzle<vector_type, array_type, 3, 0, 0, 0> xxx;
swizzle<vector_type, array_type, 3, 0, 0, 1> xxy;
swizzle<vector_type, array_type, 3, 0, 1, 0> xyx;
swizzle<vector_type, array_type, 3, 0, 1, 1> xyy;
swizzle<vector_type, array_type, 3, 1, 0, 0> yxx;
swizzle<vector_type, array_type, 3, 1, 0, 1> yxy;
swizzle<vector_type, array_type, 3, 1, 1, 0> yyx;
swizzle<vector_type, array_type, 3, 1, 1, 1> yyy;
};
};
template <typename V, typename T>
struct swizzle_array<V, T, 3>
{
typedef T value_type;
typedef std::array<value_type, 3> array_type;
typedef V vector_type;
union
{
array_type v;
struct // todo: alignment, padding?
{
value_type x;
value_type y;
value_type z;
};
swizzle<vector_type, array_type, 2, 0, 0> xx;
swizzle<vector_type, array_type, 2, 0, 1> xy;
swizzle<vector_type, array_type, 2, 0, 2> xz;
swizzle<vector_type, array_type, 2, 1, 0> yx;
swizzle<vector_type, array_type, 2, 1, 1> yy;
swizzle<vector_type, array_type, 2, 1, 2> yz;
swizzle<vector_type, array_type, 2, 2, 0> zx;
swizzle<vector_type, array_type, 2, 2, 1> zy;
swizzle<vector_type, array_type, 2, 2, 2> zz;
swizzle<vector_type, array_type, 3, 0, 0, 0> xxx;
swizzle<vector_type, array_type, 3, 0, 0, 1> xxy;
swizzle<vector_type, array_type, 3, 0, 0, 2> xxz;
swizzle<vector_type, array_type, 3, 0, 1, 0> xyx;
swizzle<vector_type, array_type, 3, 0, 1, 1> xyy;
swizzle<vector_type, array_type, 3, 0, 1, 2> xyz;
swizzle<vector_type, array_type, 3, 1, 0, 0> yxx;
swizzle<vector_type, array_type, 3, 1, 0, 1> yxy;
swizzle<vector_type, array_type, 3, 1, 0, 2> yxz;
swizzle<vector_type, array_type, 3, 1, 1, 0> yyx;
swizzle<vector_type, array_type, 3, 1, 1, 1> yyy;
swizzle<vector_type, array_type, 3, 1, 1, 2> yyz;
swizzle<vector_type, array_type, 3, 1, 2, 0> yzx;
swizzle<vector_type, array_type, 3, 1, 2, 1> yzy;
swizzle<vector_type, array_type, 3, 1, 2, 2> yzz;
swizzle<vector_type, array_type, 3, 2, 0, 0> zxx;
swizzle<vector_type, array_type, 3, 2, 0, 1> zxy;
swizzle<vector_type, array_type, 3, 2, 0, 2> zxz;
swizzle<vector_type, array_type, 3, 2, 1, 0> zyx;
swizzle<vector_type, array_type, 3, 2, 1, 1> zyy;
swizzle<vector_type, array_type, 3, 2, 1, 2> zyz;
swizzle<vector_type, array_type, 3, 2, 2, 0> zzx;
swizzle<vector_type, array_type, 3, 2, 2, 1> zzy;
swizzle<vector_type, array_type, 3, 2, 2, 2> zzz;
};
};
}
}
/Flibble
--
"Snakes didn't evolve, instead talking snakes with legs changed into snakes." - Rick C. Hodgin
“You won’t burn in hell. But be nice anyway.” – Ricky Gervais
“I see Atheists are fighting and killing each other again, over who doesn’t believe in any God the most. Oh, no..wait.. that never happens.” – Ricky Gervais
"Suppose it's all true, and you walk up to the pearly gates, and are confronted by God," Byrne asked on his show The Meaning of Life. "What will Stephen Fry say to him, her, or it?"
"I'd say, bone cancer in children? What's that about?" Fry replied.
"How dare you? How dare you create a world to which there is such misery that is not our fault. It's not right, it's utterly, utterly evil."
"Why should I respect a capricious, mean-minded, stupid God who creates a world that is so full of injustice and pain. That's what I would say."
Back to comp.lang.c++ | Previous | Next — Next in thread | Find similar | Unroll thread
Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-18 21:34 +0000
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Öö Tiib <ootiib@hot.ee> - 2019-12-18 14:24 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-18 23:14 +0000
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Öö Tiib <ootiib@hot.ee> - 2019-12-18 15:36 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-19 06:18 +0000
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-12-19 10:49 +0100
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Manfred <noname@add.invalid> - 2019-12-19 14:29 +0100
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-12-18 15:38 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-19 06:19 +0000
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-12-23 10:34 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-12-28 00:30 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibble@i42.removethisbit.co.uk> - 2019-12-28 15:53 +0000
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-01-31 23:00 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Manfred <noname@add.invalid> - 2019-12-19 14:25 +0100
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) woodbrian77@gmail.com - 2019-12-20 08:22 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Mr Flibble <flibbleREMOVETHISBIT@i42.co.uk> - 2019-12-21 13:23 +0000
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-01-11 15:08 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) Bonita Montero <Bonita.Montero@gmail.com> - 2020-02-10 18:35 +0100
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-02-10 14:07 -0800
Re: Probably UB but I am finding it hard to give a fuck (C++ swizzle) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2020-01-31 21:42 -0800
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